The research which I propose here will address the general question of how the cell cycle can be regulated by developmental signals, with the specific goal of investigating the pathway(s) that enable the delay of meiotic division in Drosophila males until all spermatid differentiation genes are transcribed. Initial work in several labs has implicated Twine, the male meiosis-specific Cdc25, as an important player in the G2/M transition. The onset of meiotic division is known to require Twine activity; in addition, the translation of twine depends on wild-type function of several genes, including three encoding testis-specific TBP-associated factors (TAFs, can, mia, and sa), and an RNA-binding protein (Boule). The work proposed here will address the connection between the transcription factors, Boule, and twine translation. First, I will identify the mechanism by which Boule protein accumulation is controlled, since it is known to be absent in sa and mia mutants. Second, I will characterize the shortstop mutant and investigate the molecular mode of action of its wild-type product.